Quantitative analyses in nuclear medicine are increasingly used, both for diagnostic and therapeutic purposes. The Partial Volume Effect (PVE) is the most important factor of loss of quantification in Nuclear Medicine, especially for evaluation in Region of Interest (ROI) smaller than the Full Width at Half Maximum (FWHM) of the PSF. The aim of this work is to present a new approach for the correction of PVE, using a post-reconstruction process starting from a mathematical expression, which only requires the knowledge of the FWHM of the final PSF of the imaging system used. After the presentation of the theoretical derivation, the experimental evaluation of this method is performed using a PET/CT hybrid system and acquiring the IEC NEMA phantom with six spherical “hot” ROIs (with diameters of 10, 13, 17, 22, 28, and 37 mm) and a homogeneous “colder” background. In order to evaluate the recovery of quantitative data, the effect of statistical noise (different acquisition times), tomographic reconstruction algorithm with and without time-of-flight (TOF) and different signal-to-background activity concentration ratio (3:1 and 10:1) was studied. The application of the corrective method allows recovering the loss of quantification due to PVE for all sizes of spheres acquired, with a final accuracy less than 17%, for lesion dimensions larger than two FWHM and for acquisition times equal to or greater than two minutes.

The most widely used method in Europe to estimate breast dosimetry in mammography is based on Dance's publications. Recently, AAPM and EFOMP joint Task Group 282 (TG282) has published a new breast dosimetry model, which improves the accuracy in Average Glandular Dose (AGD) estimation. This multicentre study aims to evaluate variations in AGD between conventional and new dosimetry across different modalities and mammography systems. Measurements were conducted on 74 mammography systems from six vendors, installed in hospitals across Italy. Each facility used its own equipment while adhering to the same protocol and spreadsheets. Tube output and Half-Value Layer (HVL) were measured in the two configurations for Digital Mammography (DM), Digital Breast Tomosynthesis (DBT), and Contrast-Enhanced Mammography (CEM). Exposures were performed using a breast-shaped PMMA phantom of different thicknesses. Data were centrally collected to compute AGD using appropriate correction factors for conventional dosimetry and the BreastAGD282 software for TG282 dosimetry, using EU legacy model. The sample allows for the identification of typical AGD values for both methodologies. The study highlights a reduction in median AGD with the new dosimetry model compared to Dance method across all modalities and vendors. Furthermore, the reduction magnitude depends on x-ray beam quality, modality and compressed breast thickness, ranging from 6.1-8.4 % at 21 mm to 27.3-38.3 % at 90 mm. The new TG282 dosimetry model showed a reduction in the estimated median AGD. Notably, the magnitude of this reduction depended on x-ray beam quality, modality and compressed breast thickness.